As the presently known method for the production of SiC whisker, there are a solid phase process using solid starting materials of carbon and silicon, and a vapor phase process using gases of carbon and silicon or reaction of solid therewith or a mixed gas.
The solid phase process is a method of leading the following reactions from solid SiO.sub.2 and C; EQU SiO.sub.2 +C.revreaction.SiO+CO EQU SiO+3CO.revreaction.SiC+2CO.sub.2 EQU CO.sub.2 +C.revreaction.2CO
and is a technique in which so-called gaseous SiO and CO produced are reacted to deposit and grow SiC whisker.
For example, the technique disclosed in Japanese Patent Application Publication No. 59-9516 belonging to such a solid phase process is a method wherein incinerated chaffs are used as Si source and carbon black is used as C source and both materials are heated in a range of 1300.degree. to 1700.degree. C. in a non-oxidizing atmosphere.
Furthermore, in the technique disclosed in Japanese Patent laid open No. 61-227993, there is proposed a method wherein anhydrous silicic acid is used as Si source and activated carbon is used as C source and both are heated at a temperature in the range of 1400.degree. to 1700.degree. C. in a non-oxidizing atmosphere.
As the apparatus used for carrying out the above solid phase process, for instance, a raction vessel for the production of SiC whisker made of a graphite is disclosed in Japanese Utility Model Application Publication No. 59-38447, and Japanese Patent laid open No. 61-227999 proposes an apparatus for the production of SiC whisker comprising a furnace body provided in its longitudinal direction with a passage having a temperature gradient, and a plurality of sample housing vessels having a starting material filling zone arranged along the passage, a whisker producing zone and an exhaust tube.
On the other hand, as the vapor phase process, there are known a method wherein a halogenated silicon such as gaseous silicon tetrachloride or the like as Si source and a gaseous carbon compound such as carbon tetrachloride or the like are reacted at a high temperature in a stream of hydrogen, a method by thermal decomposition of an organic silane such as methyltrichloro silane, and the like. For instance, the technique disclosed in Japanese Patent Application Publication No. 59-45635 is a method wherein a halogenated silicon gas and a halogenated carbon gas are introduced into a heating reaction tube through a carrier gas (H.sub.2) and then .beta.-SiC whisker is grown on a SiC or SiC-containing bottomed cylindrical substrate provided with plural slits, while Japanese Patent Application Publication No. 59-45636 proposes a method wherein a porcelain tube or a graphite tube filled with carbon powder is inserted into an outer sleeve and heated at 1300.degree. C. to generate a mixed gas of silicon tetrachloride and hydrogen to thereby produce SiC whisker.
The above two techniques as the solid phase process have the following problems:
(1) Not only a large amount of granular SiC is by-produced, but also the granules of the unreacted starting material remain, which are included in the resulting SiC whisker, so that it is impossible to obtain high-purity whisker suitable as a reinforcing material for metal or ceramics. Therefore, it is required to take complicated steps for depositing and refining these granules, and the yield of the whisker is low;
(2) Since the reaction rate is slow, it is difficult to largely and continuously produce whiskers having a high aspect ratio; and
(3) The reaction temperature is high.
Furthermore, all of the apparatuses using such a solid phase process are batch type, so that not only the continuous production is impossible, but also in order to conduct the efficient mass production, many reaction vessels should be used. Therefore, large-scaling of the apparatus comes into problem.
On the other hand, the above conventional techniques as the vapor phase process have a problem that the halogenated silicon as a starting material is expensive. And also, in these conventional techniques, there is no concrete disclosure nor suggestion on a continuous production means in industrial scale.
An object of the invention is to develop a technique which can overcome the problems in each of the above solid phase process and vapor phase process.